Various approaches have been developed to securely position an actuator arm assembly in a hard disc drive during a loss of power event or shutdown of the drive such that the heads land on and are retained on a portion of the disc real estate that does not contain data. Typically, these approaches involve either positioning the actuator arm onto a shelf to hold the heads away from the discs or positioning the heads over a portion of the disc surface that contains no data, such as the landing zones of the discs. The landing zone typically contains no magnetic recorded information or alternatively contains only historical servo information that is not pertinent to drive operation if damaged by the heads actually contacting the surface of the discs in this location. Approaches of holding the arm assembly in position include mechanical latches, electromechanical latches and magnetic latches. U.S. Pat. Nos. 5,568,333; 5,023,736; 5,483,399; 5,025,335 and 5,187,627 are representative of such latch devices.
To limit the range of motion of the actuator and heads under loss of power conditions and keep the heads in the landing zone, designers usually incorporate a crash stop with a latch mechanism to position and hold the arm in the park position while the drive is without power or actually turned off. One of the concerns in providing a resilient latch and crash stop device is the level of energy absorption by the latch device. It is desirable that the latch device absorb the impact of the actuator stopping without detrimentally affecting the head disc interface, even though the actuator arm is designed to stop in a position away from the data region of the discs where the heads are in a "park" position. If excessive impact were to occur, the heads or the disc surface itself could be damaged by head slap. Consequently crash stops may incorporate some type of rubber or elastomeric cushion and limit impact deflection so as to keep the heads from moving out of the landing zone onto the data region of the disc. Prior art stop designs incorporated little linear damping however, and sometimes the stop may deflect upward or downward from a direct impact line with the actuator tab (latching feature) because of its structural design and therefore may generate wear particles and/or generate undesirable resonances in the drive which can have undesirable effects on the head/disc interface in addition to resulting in excessive head movement.